2017 CA DWR Lidar: Sacramento Delta, CA

Dataset Description: The CA Central Valley Lidar 2016 D16 Mod 002: CA Sacramento Delta Lidar 2017 D16 lidar project called for the planning, acquisition, processing, and production of derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meters. Project specifications were based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2

Ground Conditions: Lidar was collected from December 9, 2017 through January 21, 2018 by Woolpert, while no snow was on the ground and rivers were at or below normal levels. Saturated or partially flooded farm fields were identified following data acquisition. Through technical guidance discussions with USGS and the California Department of Water, it was determined such areas shall not be considered hydrologic features. Intermittently, partially flooded, irregular, and apparently non-agricultural fields were treated as hydrologic features. In all cases, best professional judgement was used in determination of treatment. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Woolpert established 35 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 143 independent accuracy checkpoints (75 NVA points and 68 VVA points), were collected and used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

In addition to these lidar point data, the bare earth Digital Elevation Models (DEM) created from the lidar point data are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Data was collected to be used for the following: terrain mapping, conservation planning and design, support of easement/land stewardship programs, support of special emphasis programs, support of soil projects, fill gaps in existing lidar, water resource management.

USGS Contract No. G16PC00022 Task Order No. G16PD01047 (Mod 002). CONTRACTOR: Woolpert

-<lidar>

-<ldrinfo>

<ldrspec>USGS NGP Base Specifications v1.2</ldrspec>

<ldrsens>Leica ALS 80 (A-Flights)</ldrsens>

<ldrmaxnr>Unlimited</ldrmaxnr>

<ldrnps>0.35</ldrnps>

<ldrdens>8</ldrdens>

<ldranps>0.35</ldranps>

<ldradens>8</ldradens>

<ldrfltht>1524</ldrfltht>

<ldrfltsp>130</ldrfltsp>

<ldrscana>20</ldrscana>

<ldrscanr>50.0</ldrscanr>

<ldrpulsr>371.0</ldrpulsr>

<ldrpulsd>5</ldrpulsd>

<ldrpulsw>2.5</ldrpulsw>

<ldrwavel>1064</ldrwavel>

<ldrmpia>1</ldrmpia>

<ldrbmdiv>0.20</ldrbmdiv>

<ldrswatw>537</ldrswatw>

<ldrswato>25</ldrswato>

<ldrgeoid>GEOID12B</ldrgeoid>

</ldrinfo>

-<ldrinfo>

<ldrspec>USGS NGP Base Specifications v1.2</ldrspec>

<ldrsens>Leica ALS 80 (B-Flights)</ldrsens>

<ldrmaxnr>Unlimited</ldrmaxnr>

<ldrnps>0.35</ldrnps>

<ldrdens>8</ldrdens>

<ldranps>0.35</ldranps>

<ldradens>8</ldradens>

<ldrfltht>1829</ldrfltht>

<ldrfltsp>130</ldrfltsp>

<ldrscana>20</ldrscana>

<ldrscanr>58.0</ldrscanr>

<ldrpulsr>451.0</ldrpulsr>

<ldrpulsd>5</ldrpulsd>

<ldrpulsw>2.5</ldrpulsw>

<ldrwavel>1064</ldrwavel>

<ldrmpia>1</ldrmpia>

<ldrbmdiv>0.20</ldrbmdiv>

<ldrswatw>455</ldrswatw>

<ldrswato>25</ldrswato>

<ldrgeoid>GEOID12B</ldrgeoid>

</ldrinfo>

-<ldraccur>

<ldrchacc>0</ldrchacc>

<rawnva>0.107</rawnva>

<rawnvan>75</rawnvan>

<clsnva>0.099</clsnva>

<clsnvan>75</clsnvan>

<clsvva>0.289</clsvva>

<clsvvan>68</clsvvan>

</ldraccur>

-<lasinfo>

<lasver>1.4</lasver>

<lasprf>6</lasprf>

<laswheld>Geometrically unreliable points were identified using a combination of automated and manual techniques and subsequently classified as high or low noise and given the standard Withheld bit.</laswheld>

<lasolap>Swath "overage" points were identified in these files using the standard LAS overlap bit.</lasolap>

<lasintr>16</lasintr>

-<lasclass>

<clascode>1</clascode>

<clasitem>Processed but not classified</clasitem>

</lasclass>

-<lasclass>

<clascode>2</clascode>

<clasitem>Bare earth ground</clasitem>

</lasclass>

-<lasclass>

<clascode>7</clascode>

<clasitem>Noise</clasitem>

</lasclass>

-<lasclass>

<clascode>9</clascode>

<clasitem>Water</clasitem>

</lasclass>

-<lasclass>

<clascode>10</clascode>

<clasitem>Ignored ground</clasitem>

</lasclass>

-<lasclass>

<clascode>17</clascode>

<clasitem>Bridge Decks</clasitem>

</lasclass>

-<lasclass>

<clascode>18</clascode>

<clasitem>High Noise</clasitem>

</lasclass>

</lasinfo>

</lidar>

None. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data. The information contained in these data is dynamic and may change over time. The data are not better than the original sources from which they were derived. It is the responsibility of the data user to use the data appropriately and within the limitations of the data for which it was requested and prepared, in general, and these data in particular. The related graphics are intended to aid the data user in acquiring relevant data. It is not appropriate to use the related graphics as data. Woolpert gives no warranty, expressed or implied, as to the accuracy, reliability, or completeness of these data. It is strongly recommended that these data are directly acquired from a Woolpert server, and not indirectly through other sources which may have changed the data in some way. Although these data have been processed successfully upon Woolpert'20190603s computer system, no warranty, expressed or implied, is made regarding the utility of the data on another system, or for general or scientific purposes; nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk and custom downloads.

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

Microsoft Windows 10 Version 1607 (Build 14393.2189); ArcMap 10.3; ArcCatalog 10.3; TerraScan ver. 17; TerraModeler ver. 17; Geocue 2017.2.20.0.

The project specifications require that only Non-Vegetated Vertical Accuracy (NVA) be computed for raw lidar point cloud swath files. The required accuracy (ACCz) is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in non-vegetated land cover classes. The NVA was tested with 75 checkpoints located in bare earth and urban (non-vegetated) areas. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the unclassified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standard for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

Tested 0.107 meters NVA at a 95% confidence level using RMSE(z) 0.055 x 1.9600 as defined by the National Standard for Spatial Data Accuracy (NSSDA). The NVA of the raw lidar point cloud swath files was calculated against TINs derived from the final calibrated and controlled swath data using 75 independent checkpoints located in non-vegetated land cover categories.

These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist.

Data covers the entire area specified for this project.

This data set was downloaded from the CA DWR http site and processed to make it available for custom download from the Data Access Viewer (DAV) and for bulk download from https.